HR 4887

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HR 4887

NGC 4755, with HR 4887 on the right
Credit: ESO/Y. Beletsky
Observation data
Epoch J2000      Equinox J2000
Constellation Crux
Right ascension 12h 53m 21.89463s[1]
Declination −60° 19′ 46.5630″[1]
Apparent magnitude (V) 5.77[2]
Characteristics
Spectral type B9 Ia[3]
U−B color index −0.34[4]
B−V color index +0.32[4]
Variable type α Cyg?[5]
Distance
approx. 9,000 ly
(approx. 2,800 pc)
Absolute magnitude (MV)−7.00[8]
Details
Myr
HIP 62894, 2MASS J12532189-6019424, NSV
 6008
Database references
SIMBADdata

HR 4887 (HD 111904) is a suspected

NGC 4755
, which is also known as the Kappa Crucis Cluster or Jewel Box Cluster.

Location

β Crucis
(Credit: ESO, ESA/Hubble and Digitized Sky Survey 2. Acknowledgment: Davide De Martin)

HR 4887 is one of the brightest members of the NGC 4775 open cluster, better known as the Jewel Box Cluster.[9] It forms the apex of the prominent letter "A" asterism at the centre of the cluster. The cluster is part of the larger Centaurus OB1 association and lies about 8,500 light years away.

The cluster, and HR 4887 itself, is just to the south-east of

Southern Cross
.

Properties

HR 4887 is a B9

bright supergiant (luminosity class Ia). It is over 100,000 times the luminosity of the sun, partly due to its higher temperature over 12,680 K, and partly to being seventy times larger than the sun. The κ Crucis cluster has a calculated age of 11.2 million years, and HR 4887 itself eight million years.[8]

In 1958, HR 4887 was reported to be at visual magnitude 6.80 and on this basis is included in the New Catalogue of Suspected Variable Stars with a range of variation of 5.70 - 6.80.[10] No other observer has measured it far from magnitude 5.75, but measurements of known variable class B stars found that HR 4887 is variable by about a tenth of a magnitude. It is thought likely to be an α Cygni-type variable.[5]

References

  1. ^
    S2CID 18759600
    .
  2. doi:10.1888/0333750888/2862
    .
  3. S2CID 15874925
    .
  4. ^
    Bibcode:1984A&AS...58..411D
    .
  5. ^
    S2CID 8783008
    .
  6. S2CID 119231169
    .
  7. ^
    doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR
    .
  8. ^
    hdl:11336/145136
    .
  9. doi:10.1002/asna.200410256
    .
  10. Bibcode:2009yCat....102025S
    .

External links
Retrieved from "https://en.wikipedia.org/w/index.php?title=HR_4887&oldid=1195821704"